Stage assembly with measurement system initialization, vibration compensation, low transmissibility, and lightweight fine stage

ABSTRACT

A stage assembly ( 220 ) that moves a work piece ( 200 ) about a first axis and along a first axis includes a first stage ( 238 ), a second stage ( 240 ) that retains the work piece ( 200 ), a second mover assembly ( 244 ), a measurement system, and an initialization system ( 1081 A). The second mover assembly ( 244 ) moves the second stage ( 240 ) relative to the first stage ( 238 ) about the first axis. The measurement system ( 22 ) monitors the position of the second stage ( 240 ) about the first axis when the second stage ( 240 ) is positioned within a working range about the first axis. The initialization system ( 1081 A) facilitates movement of the second stage ( 240 ) about the first axis when the second stage ( 240 ) is rotated about the first axis outside the working range. The second mover assembly ( 244 ) can include a mover ( 255 ) and a dampener ( 410 ) that reduces the transmission of vibration from the first stage ( 238 ) to the second stage ( 240 ). In addition, the stage assembly ( 220 ) can include a control system ( 24 ) that directs power to the mover ( 255 ) to position the second stage ( 240 ) and to compensate for vibration of the first stage ( 238 ).

RELATED APPLICATION

This application is a continuation-in-part of U.S. application Ser. No.11/048,405 filed on Jan. 31, 2005, and entitled “Stage Assembly withLightweight Fine Stage and Low Transmissibility” which is currentlypending. This application also claims priority on U.S. ProvisionalApplication Ser. No. 60/624,385 filed on Nov. 2, 2004 and entitled “FINESTAGE DESIGN”, U.S. Provisional Application Ser. No. 60/625,699 filed onNov. 4, 2004 and entitled “Z ACTUATOR”, and U.S. Provisional ApplicationSer. No. 60/647,901 filed on Jan. 28, 2005 and entitled “FINE STAGE ‘Z’ACTUATOR DEVICE AND METHOD”. As far as is permitted, the contents ofU.S. application Ser. No. 11/048,405, and U.S. Provisional ApplicationSer. Nos. 60/624,385; 60/625,699; and 60/647,901 are incorporated hereinby reference.

BACKGROUND

Exposure apparatuses for semiconductor processing are commonly used totransfer images from a reticle onto a semiconductor wafer duringsemiconductor processing. A typical exposure apparatus includes anillumination source, a reticle stage assembly that positions a reticle,an optical assembly, a wafer stage assembly that positions asemiconductor wafer, a measurement system, and a control system.

A common type of stage assembly includes a coarse stage, a coarse moverassembly that moves the coarse stage, a fine stage, and a fine moverassembly that moves the fine stage. With this design, the measurementsystem constantly monitors the position of the fine stage.

With certain stage designs, vibration and disturbances from the groundor the environment are transferred to the coarse stage and subsequentlytransmitted to the fine stage. This can cause errors in the positioningof the fine stage. The size of the images and features within the imagestransferred onto the wafer from the reticle are extremely small. As aresult thereof, the precise positioning of the wafer and the reticle iscritical to the manufacture of high density, semiconductor wafers.

SUMMARY

The present invention is directed to a stage assembly that moves a workpiece. The stage assembly includes a first stage, a second stage thatretains the work piece, a second mover assembly that moves the secondstage relative to the first stage about a first axis, a measurementsystem, and an initialization system. The measurement system monitorsthe position of the second stage about the first axis when the secondstage is positioned within a FA working range about the first axis. Theinitialization system facilitates movement of the second stage about thefirst axis when the second stage is rotated about the first axis outsidethe FA working range.

In one embodiment, the measurement system monitors the position of thesecond stage about a second axis when the second stage is positionedwithin the SA working range about the second axis and/or monitors theposition of the second stage about a third axis when the second stage ispositioned within the TA working range about the third axis. In thisembodiment, the initialization system monitors the position of thesecond stage about the first, second, and/or third axes.

In another embodiment, the initialization system includes a firstaligner. In this embodiment, the second mover assembly moves the secondstage against the first aligner to orient and align the second stagewithin the FA working range. Additionally, the initialization system caninclude a second aligner. In this embodiment, the second mover assemblymoves the second stage against the second aligner to orientate and alignthe second stage within the SA working range.

In still another embodiment, the second mover assembly moves the secondstage relative to the first stage along the first axis. The second moverassembly includes a mover and a dampener that influences thetransmission of vibration from the first stage to the second stage. Inone embodiment, the stage assembly includes a control system thatdirects power to the mover to position the second stage and to at leastpartly compensate for vibration of the first stage being transferred viathe dampener.

The present invention is also directed a stage assembly that moves awork piece along a first axis, along a second axis and along a thirdaxis. The stage assembly includes a first stage, a first mover assemblythat moves the first stage along the first axis, a second stage thatretains the work piece, a second mover assembly, and a non-contactbearing. In certain embodiments, the second mover assembly moves thesecond stage relative to the first stage along the first axis, along thesecond axis, and along the third axis. Further, the non-contact bearingsupports the mass of the second stage and the non-contact bearing allowsthe second stage to move relative to the first stage along the firstaxis and along the second axis.

In one embodiment, the second mover assembly moves the second stage withat least four degrees of movement. In another embodiment, the secondmover assembly moves the second stage with at least six degrees ofmovement.

The second mover assembly includes a Z mover that moves the second stagerelative to the first stage along the third axis. In this design, thenon-contact bearing supports the second stage relative to the Z mover.The Z mover includes a Z housing, a Z mover output, and a connectorassembly that allows the Z mover output to tilt relative to the Zhousing. In one embodiment, the second mover assembly includes threespaced apart Z movers that move the second stage relative to the firststage along the third axis, about the first axis, and about the secondaxis, and the non-contact bearing supports the second stage relative tothe Z movers.

In one embodiment, the Z mover includes a first mover component, asecond mover component that interacts with the first mover component tomove the second stage relative to the first stage along the third axis,and a Z dampener that inhibits vibration from the first stage along thethird axis from being transmitted to the second stage.

In another embodiment, the second stage includes a stage mountingsurface. Further, the second mover assembly includes a first movercomponent that is coupled to the first stage and a second movercomponent that is coupled to the second stage. In this embodiment, thesecond mover component includes a mover mounting surface that engagesthe stage mounting surface. In one embodiment, the mover mountingsurface cantilevers away from the stage mounting surface so thatdeformation of the second mover component occurs without deformation ofthe stage mounting surface.

In still another embodiment, the stage assembly includes a coarse stage,a coarse mover assembly that moves the coarse stage, a fine stage thatretains the work piece, and a fine mover assembly that moves the finestage relative to the coarse stage. In one version, the fine stageincludes an upper plate, a lower plate and a plurality of walls that arepositioned between the plates.

In still another embodiment, the stage assembly includes a fluid sourceof a fluid at a reduce pressure, a first stage, a second stage thatincludes a chuck that retains the work piece, a mover assembly thatmoves the second stage relative to the first stage, and a bearingassembly that supports the second stage relative to the first stage. Inthis embodiment, the second stage includes a bearing surface having aninlet port that is in fluid communication with the chuck. Further, thebearing assembly is in fluid communication with the fluid source so thatthe fluid at the reduced pressure is in fluid communication with theinlet port and the chuck.

Further, the present invention is also directed to a method for moving astage, a method for manufacturing an exposure apparatus, and a methodfor manufacturing an object or a wafer.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of this invention, as well as the invention itself,both as to its structure and its operation, will be best understood fromthe accompanying drawings, taken in conjunction with the accompanyingdescription, in which similar reference characters refer to similarparts, and in which:

FIG. 1 is a schematic illustration of an exposure apparatus havingfeatures of the present invention;

FIG. 2A is a simplified side view of one embodiment of a stage assemblyhaving features of the present invention;

FIG. 2B is a perspective view of a portion of the stage assembly of FIG.2A;

FIG. 2C is another perspective view of a portion of the stage assemblyof FIG. 2A;

FIG. 2D is a front plan view of the portion of the stage assembly ofFIG. 2C;

FIG. 3A is a top perspective of a portion a stage assembly and a workpiece;

FIG. 3B is a perspective view of a mirror having features of the presentinvention;

FIG. 3C is a top view of the mirror of FIG. 3B;

FIG. 3D is a top view of a portion of the mirror of FIG. 3C;

FIG. 3E is a bottom perspective of a portion a stage assembly;

FIG. 3F is a simplified illustration of a portion of a stage assembly;

FIG. 3G is a perspective view of a portion of an X mover;

FIGS. 3H and 3I are alternative, exploded perspective views of a table;

FIG. 3J is an exploded perspective view of yet another embodiment of atable;

FIG. 4A is a perspective view of a Z mover;

FIG. 4B is a cross-sectional perspective view of a portion of the Zmover;

FIG. 4C is a cross-sectional plan view of a portion of the Z mover;

FIG. 4D is an enlarged cross-sectional plan view of a portion of the Zmover;

FIG. 5 is a simplified illustration of a portion of the stage assembly;

FIG. 6A is a top perspective of another embodiment of a portion a stageassembly;

FIG. 6B is a bottom perspective of the portion of the stage assembly ofFIG. 6A;

FIG. 7A is a top perspective of another embodiment of a portion a stageassembly;

FIG. 7B is a side perspective of the portion of the stage assembly ofFIG. 7A;

FIG. 8 is a simplified illustration of another embodiment of portion ofa stage assembly;

FIG. 9A is a simplified schematic of a portion of a stage assemblyhaving features of the present invention;

FIG. 9B is a simplified control diagram that illustrates the controlfunction of a portion of the stage assembly of FIG. 9A;

FIGS. 9C-9E are alternative graphs that illustrate simulated dataregarding transmissibility compensation;

FIGS. 9F and 9G are graphs that illustrate the effect of stiffnesscompensation;

FIG. 10A is a simplified schematic of a yet another embodiment of aportion of a stage assembly having features of the present invention;

FIG. 10B is a simplified schematic of a still another embodiment of aportion of a stage assembly having features of the present invention;

FIG. 10C is a simplified schematic of another embodiment of a portion ofa stage assembly having features of the present invention;

FIG. 11A is a flow chart that outlines a process for manufacturing adevice in accordance with the present invention; and

FIG. 11B is a flow chart that outlines device processing in more detail.

DESCRIPTION

FIG. 1 is a schematic illustration of a precision assembly, namely anexposure apparatus 10 having features of the present invention. Theexposure apparatus 10 includes an apparatus frame 12, an illuminationsystem 14 (irradiation apparatus), an optical assembly 16, a reticlestage assembly 18, a wafer stage assembly 20, a measurement system 22,and a control system 24. The design of the components of the exposureapparatus 10 can be varied to suit the design requirements of theexposure apparatus 10.

A number of Figures include an orientation system that illustrates an Xaxis, a Y axis that is orthogonal to the X axis and a Z axis that isorthogonal to the X and Y axes. It should be noted that these axes canalso be referred to as the first, second and third axes.

The exposure apparatus 10 is particularly useful as a lithographicdevice that transfers a pattern (not shown) of an integrated circuitfrom a reticle 26 onto a semiconductor wafer 200 (illustrated in FIG.2B). The exposure apparatus 10 mounts to a mounting base 30, e.g., theground, a base, or floor or some other supporting structure.

There are a number of different types of lithographic devices. Forexample, the exposure apparatus 10 can be used as a scanning typephotolithography system that exposes the pattern from the reticle 26onto the wafer 200 with the reticle 26 and the wafer 200 movingsynchronously. In a scanning type lithographic device, the reticle 26 ismoved perpendicularly to an optical axis of the optical assembly 16 bythe reticle stage assembly 18 and the wafer 200 is moved perpendicularlyto the optical axis of the optical assembly 16 by the wafer stageassembly 20. Scanning of the reticle 26 and the wafer 200 occurs whilethe reticle 26 and the wafer 200 are moving synchronously.

Alternatively, the exposure apparatus 10 can be a step-and-repeat typephotolithography system that exposes the reticle 26 while the reticle 26and the wafer 200 are stationary. In the step and repeat process, thewafer 200 is in a constant position relative to the reticle 26 and theoptical assembly 16 during the exposure of an individual field.Subsequently, between consecutive exposure steps, the wafer 200 isconsecutively moved with the wafer stage assembly 20 perpendicularly tothe optical axis of the optical assembly 16 so that the next field ofthe wafer 200 is brought into position relative to the optical assembly16 and the reticle 26 for exposure. Following this process, the imageson the reticle 26 are sequentially exposed onto the fields of the wafer200, and then the next field of the wafer 200 is brought into positionrelative to the optical assembly 16 and the reticle 26.

However, the use of the exposure apparatus 10 provided herein is notlimited to a photolithography system for semiconductor manufacturing.The exposure apparatus 10, for example, can be used as an LCDphotolithography system that exposes a liquid crystal display devicepattern onto a rectangular glass plate or a photolithography system formanufacturing a thin film magnetic head. Further, the present inventioncan also be applied to a proximity photolithography system that exposesa mask pattern from a mask to a substrate with the mask located close tothe substrate without the use of a lens assembly.

The apparatus frame 12 is rigid and supports the components of theexposure apparatus 10. The apparatus frame 12 illustrated in FIG. 1supports the reticle stage assembly 18, the optical assembly 16 and theillumination system 14 above the mounting base 30.

The illumination system 14 includes an illumination source 32 and anillumination optical assembly 34. The illumination source 32 emits abeam (irradiation) of light energy. The illumination optical assembly 34guides the beam of light energy from the illumination source 32 to theoptical assembly 16. The beam illuminates selectively different portionsof the reticle 26 and exposes the wafer 200. In FIG. 1, the illuminationsource 32 is illustrated as being supported above the reticle stageassembly 18. Typically, however, the illumination source 32 is securedto one of the sides of the apparatus frame 12 and the energy beam fromthe illumination source 32 is directed to above the reticle stageassembly 18 with the illumination optical assembly 34.

The illumination source 32 can be a g-line source (436 nm), an i-linesource (365 nm), a KrF excimer laser (248 nm), an ArF excimer laser (193nm) or a F₂ laser (157 nm). Alternatively, the illumination source 32can generate charged particle beams such as an x-ray or an electronbeam. For instance, in the case where an electron beam is used,thermionic emission type lanthanum hexaboride (LaB₆) or tantalum (Ta)can be used as a cathode for an electron gun. Furthermore, in the casewhere an electron beam is used, the structure could be such that eithera mask is used or a pattern can be directly formed on a substratewithout the use of a mask.

The optical assembly 16 projects and/or focuses the light passingthrough the reticle 26 to the wafer 200. Depending upon the design ofthe exposure apparatus 10, the optical assembly 16 can magnify or reducethe image illuminated on the reticle 26. The optical assembly 16 neednot be limited to a reduction system. It could also be a 1× ormagnification system.

When far ultra-violet rays such as the excimer laser is used, glassmaterials such as quartz and fluorite that transmit far ultra-violetrays can be used in the optical assembly 16. When the F₂ type laser orx-ray is used, the optical assembly 16 can be either catadioptric orrefractive (a reticle should also preferably be a reflective type), andwhen an electron beam is used, electron optics can consist of electronlenses and deflectors. The optical path for the electron beams should bein a vacuum.

Also, with an exposure device that employs vacuum ultra-violet radiation(VUV) of wavelength 200 nm or lower, use of the catadioptric typeoptical system can be considered. Examples of the catadioptric type ofoptical system include the disclosure Japan Patent ApplicationDisclosure No. 8-171054 published in the Official Gazette for Laid-OpenPatent Applications and its counterpart U.S. Pat. No. 5,668,672, as wellas Japan Patent Application Disclosure No. 10-20195 and its counterpartU.S. Pat. No. 5,835,275. In these cases, the reflecting optical devicecan be a catadioptric optical system incorporating a beam splitter andconcave mirror. Japan Patent Application Disclosure No. 8-334695published in the Official Gazette for Laid-Open Patent Applications andits counterpart U.S. Pat. No. 5,689,377 as well as Japan PatentApplication Disclosure No. 10-3039 and its counterpart U.S. patentapplication No. 873,605 (Application Date: Jun. 12, 1997) also use areflecting-refracting type of optical system incorporating a concavemirror, etc., but without a beam splitter, and can also be employed withthis invention. As far as is permitted, the disclosures in theabove-mentioned U.S. patents, as well as the Japan patent applicationspublished in the Official Gazette for Laid-Open Patent Applications areincorporated herein by reference.

The reticle stage assembly 18 holds and positions the reticle 26relative to the optical assembly 16 and the wafer 200. Somewhatsimilarly, the wafer stage assembly 20 holds and positions the wafer 200with respect to the projected image of the illuminated portions of thereticle 26.

Further, in photolithography systems, when linear motors (see U.S. Pat.No. 5,623,853 or 5,528,118) are used in a wafer stage or a mask stage,the linear motors can be either an air levitation type employing airbearings or a magnetic levitation type using Lorentz force or reactanceforce. As far as is permitted, the disclosures in U.S. Pat. Nos.5,623,853 and 5,528,118 are incorporated herein by reference.

Alternatively, one of the stages could be driven by a planar motor,which drives the stage by an electromagnetic force generated by a magnetunit having two-dimensionally arranged magnets and an armature coil unithaving two-dimensionally arranged coils in facing positions. With thistype of driving system, either the magnet unit or the armature coil unitis connected to the stage and the other unit is mounted on the movingplane side of the stage.

Movement of the stages as described above generates reaction forces thatcan affect performance of the photolithography system. Reaction forcesgenerated by the wafer (substrate) stage motion can be mechanicallytransferred to the floor (ground) by use of a frame member as describedin U.S. Pat. No. 5,528,100 and published Japanese Patent ApplicationDisclosure No. 8-136475. Additionally, reaction forces generated by thereticle (mask) stage motion can be mechanically transferred to the floor(ground) by use of a frame member as described in U.S. Pat. No.5,874,820 and published Japanese Patent Application Disclosure No.8-330224. As far as is permitted, the disclosures in U.S. Pat. Nos.5,528,100 and 5,874,820 and Japanese Patent Application Disclosure No.8-330224 are incorporated herein by reference.

The measurement system 22 monitors movement of the reticle 26 and thewafer 200 relative to the optical assembly 16 or some other reference.With this information, the control system 24 can control the reticlestage assembly 18 to precisely position the reticle 26 and the waferstage assembly 20 to precisely position the wafer 200. For example, themeasurement system 22 can utilize multiple laser interferometers,encoders, and/or other measuring devices.

The control system 24 is connected to the reticle stage assembly 18, thewafer stage assembly 20, and the measurement system 22. The controlsystem 24 receives information from the measurement system 22 andcontrols the stage mover assemblies 18, 20 to precisely position thereticle 26 and the wafer 200. The control system 24 can include one ormore processors and circuits.

A photolithography system (an exposure apparatus) according to theembodiments described herein can be built by assembling varioussubsystems, including each element listed in the appended claims, insuch a manner that prescribed mechanical accuracy, electrical accuracy,and optical accuracy are maintained. In order to maintain the variousaccuracies, prior to and following assembly, every optical system isadjusted to achieve its optical accuracy. Similarly, every mechanicalsystem and every electrical system are adjusted to achieve theirrespective mechanical and electrical accuracies. The process ofassembling each subsystem into a photolithography system includesmechanical interfaces, electrical circuit wiring connections and airpressure plumbing connections between each subsystem. Needless to say,there is also a process where each subsystem is assembled prior toassembling a photolithography system from the various subsystems. Once aphotolithography system is assembled using the various subsystems, atotal adjustment is performed to make sure that accuracy is maintainedin the complete photolithography system. Additionally, it is desirableto manufacture an exposure system in a clean room where the temperatureand cleanliness are controlled.

FIG. 2A is a simplified view of a control system 224 and a side view ofone embodiment of a stage assembly 220 that is used to position a workpiece 200 (illustrated in FIG. 2B). For example, the stage assembly 220can be used as the wafer stage assembly 20 in the exposure apparatus 10of FIG. 1. In this embodiment, the stage assembly 220 would position thewafer 200 (illustrated in FIG. 2B) during manufacturing of thesemiconductor wafer 200. Alternatively, the stage assembly 220 can beused to move other types of work pieces 200 during manufacturing and/orinspection, to move a device under an electron microscope (not shown),or to move a device during a precision measurement operation (notshown). For example, the stage assembly 220 could be designed tofunction as the reticle stage assembly 18.

In this embodiment, the stage assembly 220 includes a stage base 236, afirst stage 238, a second stage 240, a first mover assembly 242, and asecond mover assembly 244. The size, shape, and design of each thesecomponents can be varied. The control system 224 precisely controls themover assemblies 242, 244 to precisely position the work piece 200.

In FIG. 2A, the stage base 236 supports some of the components of thestage assembly 220 and guides the movement of the first stage 238 alongthe X axis, along the Y axis and about the Z axis. In this embodiment,the stage base 236 is generally rectangular shaped.

The first stage 238 facilitates relatively large movements of the secondstage 240 and is commonly referred to as the coarse stage. In oneembodiment, the first stage 238 supports the second stage 240 and thesecond mover assembly 244. In one embodiment, the first stage 238includes an lower support 251A, an upper support 251B secured to thelower support 251A, and a stage frame 251C that supports the lowersupport 251A. In FIG. 2A, a bearing (not shown) supports the first stage238 above the stage base 236 and allows the first stage 238 to moverelative to the stage base 236 along the X axis, along the Y axis andabout the Z axis. The bearing, for example, can be a vacuum preload typefluid bearing, a magnetic type bearing or a roller type assembly.

The second stage 240 retains the work piece 200 and is commonly referredto as the fine stage. The second stage 240 is described in more detailbelow.

The first mover assembly 242 moves the first stage 238 and a portion ofthe second mover assembly 244 relative to the stage base 236. In theembodiment illustrated in FIG. 2A, the first mover assembly 242 movesthe first stage 238 with three degrees of movement, namely, along the Xaxis, along the Y axis and about the Z axis. Alternatively, for example,the first mover assembly 242 could be designed to move the first stage238 with less than three degrees of movement, or more than three degreesof movement. The first mover assembly 242 can include one or moremovers.

In FIG. 2A, the first mover assembly 242 includes a left X coarse mover246L, a right X coarse mover 246R, a Y coarse mover 246Y (illustrated inphantom), and a guide bar 248.

The X coarse movers 246L, 246R move the guide bar 248, and the firststage 238 along the X axis and with a limited range of motion about theZ axis, and the Y coarse mover 246Y moves the first stage 238 along theY axis relative to the guide bar 248. The motion about the Z axis isachieved by controlling a difference in the amount of forces generatedby the left X coarse mover 246A and the right X coarse mover 246R.

The design of each coarse mover 246L, 246R, 246Y can be varied to suitthe movement requirements of the first mover assembly 242. In theembodiment illustrated in FIG. 2A, each of the coarse movers 246L, 246R,246Y includes a first coarse component 250A and a second coarsecomponent 250B that interacts with the first coarse component 250A. Inthis embodiment, each of the coarse movers 246L, 246R, 246Y is a linearmotor and one of the coarse components 250A, 250B includes a magnetarray having one or more magnets and one of the coarse components 250B,250A includes a conductor array having one or more coils. In FIG. 2A,the first coarse component 250A of each X coarse mover 246L, 246R issecured to the stage base 236 and the second coarse component 250B ofeach X coarse mover 246L, 246R is secured to the guide bar 248. Further,the first coarse component 250A of the Y coarse mover 246Y is secured tothe guide bar 248 and the second coarse component 250B of the Y coarsemover 246Y is secured to the first stage 238.

Alternatively, one or more of the coarse movers 246L, 246R, 246Y can beanother type of motor, such as a rotary motors, a voice coil motor, anelectromagnetic mover, a planar motor, or some other force mover.

The guide bar 248 guides the movement of the first stage 238 along the Yaxis. A bearing (not shown) such as a fluid type bearing or a magnetictype bearing can be disposed between the guide bar 248 and the firststage 238. Another bearing (not shown) maintains the guide bar 248spaced apart along the Z axis relative to the stage base 236 and allowsfor motion of the guide bar 248 along the X axis and about the Z axisrelative to the stage base 236. The bearing, for example, can be avacuum preload type fluid bearing, a magnetic type bearing or a rollertype assembly.

The second mover assembly 244 moves and positions the second stage 240and the work piece 200. In FIG. 2A, the second mover assembly 244 movesthe second stage 240 with six degrees of movement, namely, along the X,Y, and Z axes, and about the X, Y, and Z axes relative to the firststage 238. Alternatively, the second mover assembly 244 could bedesigned to move the second stage 240 with less than six degrees ofmovement. The second mover assembly 244 can include one or more movers.

FIG. 2B is a perspective view of a portion of the stage assembly 220 ofFIG. 2A. More specifically, FIG. 2B illustrates the second stage 240,the second mover assembly 244, and a portion of the first stage 238,namely the lower support 251A and the upper support 251B.

FIG. 2B also illustrates one embodiment of the second mover assembly 244in more detail. In particular, in this embodiment, the second moverassembly 244 includes a first X mover 252F, a second X mover 252S, afirst Y mover 254F, a second Y mover 254S (illustrated in FIG. 3A), andthree spaced apart Z movers 255 (only two are illustrated in FIG. 2B).The X movers 252F, 252S move the second stage 240 along the X axis, theY movers 254F, 254S move the second stage 240 along the Y axis, the Zmovers 255 move the second stage 240 along the Z axis and about the Xand Y axes, and either the X movers 252F, 252S or the Y movers 254F,254S can be used to move the second stage 240 about the Z axis.

The design of each mover 252F, 252S, 254F, 254S, 255 can be varied tosuit the movement requirements of the second mover assembly 244. In theembodiment illustrated in FIG. 2B, each of the movers 252F, 252S, 254F,254S includes a first mover component 256A and a second mover component256B that interacts with the first mover component 256A. In FIG. 2B, thefirst mover component 256A of each of the X and Y movers 252F, 252S,254F, 254S is secured to the upper support 251B of the first stage 238and the second mover component 256B of each of the X and Y movers 252F,252S, 254F, 254S is secured to the second stage 240.

In this embodiment, for each mover 252F, 252S, 254F, 254S, one of themover components 256A, 256B includes a magnet array having one or moremagnets and one of the mover components 256B, 256A includes a conductorarray having one or more coils. In FIG. 2B, the first mover component256A for each of the movers 252F, 252S, 254F, 254S, 255 includes a coilarray and the second mover component 256B for each of the movers 252F,252S, 254F, 254S includes a magnet array. With this design, electricallines that power the second mover assembly 244 do not have to beconnected to the second stage 240. However, the invention is not limitedto this design. Alternately, the first mover component 256A can includethe coil array and the second mover component 256B can include themagnet array.

In FIG. 2B, each of the X movers 252F, 252S is a linear motor and eachof the Z movers 255 and the Y movers 254F, 254S is a voice coil motor.Alternatively, one or more of the movers 252F, 252S, 254F, 254S, 255 canbe another type of motor, such as a rotary motors, an electromagneticmover, a planar motor, or some other force mover. For example, each ofthe X movers 252F, 252S can be a voice coil motor.

FIG. 2C is a perspective view and FIG. 2D is a side view of the portionof the stage assembly 220 of FIG. 2B with the upper support 251B of thefirst stage 238 removed. These figures illustrate that the Z movers 255are coupled to the lower support 251A of the first stage 238. Morespecifically, the first mover component 256A is coupled to the lowersupport 251A. Also, the second mover component 256B is connected to thelower support 251A via a Z beam 408 (illustrated in FIG. 4D) and a Zdampener 410 (illustrated in FIG. 4D).

It should be noted that in this embodiment, as illustrated in FIG. 2D, asufficient gap 258 exists between the first mover component 256A and thesecond mover component 256B of the X and Y movers 252F, 252S, 254F, 254Sso that the mover components 256A, 256B do not contact each other duringthe range of movement of the second stage 240 relative to the firststage 238 along Z -axis, about X and Y axes with the Z movers 255.

In this embodiment, a stage bearing assembly 257 (illustrated as arrows)supports the second stage 240 relative to the first stage 238. In oneembodiment, the stage bearing assembly 257 supports the second stage 240relative to the Z movers 255 and allows the second stage 240 to moverelative to the Z movers 255 and the first stage 238 substantially alongthe X and Y axes and about the Z axis. In one embodiment, the stagebearing assembly 257 includes one or more non contact type bearings,such as a fluid type bearing, a vacuum preload type fluid bearing, or amagnetic type bearing. With the non contact type bearing, there is verylow transmissibility along the X and Y axes. Stated in another fashion,the non contact type bearing inhibits vibration from the first stage 238along the X and Y axes from being transmitted to the second stage 240.Moreover, with the non contact type bearing, the second stage 240 can bemoved along the X and Y axes and about the Z axis with little to nofriction. In one embodiment, the stage bearing assembly 257 includesthree spaced apart non contact type bearings to support the second stage240 in a kinematic fashion.

FIG. 3A is a perspective top view of the second stage 240, an X mirror360X and a Y mirror 360Y that is used in the measurement system 22 ofFIG. 1, a portion of the second mover assembly 244, and the work piece200. In this embodiment, the second stage 240 includes a table 362 and achuck 364 secured to the table 362 that holds the work piece 200. Thetable 362 is roughly rectangular shaped and the right side of the table362 defines a cantilevering, necked region 366A that defines a firstmounting surface 366B.

In FIG. 3A, each mirror 360X, 360Y is made of a ceramic material, has agenerally “T” shaped cross-section and includes a mirror surface andthree spaced apart, relatively thin, attachment areas 360A. One or morefasteners 360F fixedly secure the attachment areas 360A to the table362. In one embodiment, each attachment area 360A includes one or moreslots 360S positioned between the mirror surface and each attachmentarea 360A that inhibit forces and deformation caused by the fasteners360F against the attachment areas 360A from deforming the rest of therespective mirror 360X, 360Y.

FIG. 3B is a perspective view, FIG. 3C is a top view, and FIG. 3D is atop view of a portion of one of the mirrors, namely the X mirror 360X.These Figures illustrate that the one or more slots 360S separate theattachment areas 360A from the rest of the X mirror 360X. Further, theseFigures illustrate that at least one of the attachment areas 360Aincludes a fastener aperture 361A that receives one fastener 360F(illustrated in FIG. 3A) and an attachment slot 361 B that extendsbetween the fastener aperture 361A and the slot 360S. In one embodiment,the attachment slot 361B inhibits forces and deformation caused by thefastener 360F against the attachment area 360A from deforming the restof the X mirror 360X.

Referring back to FIG. 3A, the second mover component 256B of the firstX mover 252F, and the Y movers 254F, 254S are secured to the right sideof the table 362, and the second mover component 256B of the second Xmover 252S is secured to the left side of the table 362. Further, thesecond mover component 256B of the first X mover 252F is positionedbetween the second mover component 256B of the Y movers 254F, 254S. Inthis embodiment, each second mover component 256B includes a “U” shapedmover housing 368A, and a pair of spaced apart magnet arrays 368B thatare secured to the housing 368A. In one embodiment, a mounting bracket368C secures the mover housing 368A of the first X mover 252F, and the Ymovers 254F, 254S to the table 362. In one embodiment, the mountingbracket 368C is generally beam shaped.

FIG. 3E is a perspective bottom view of the second stage 240, and aportion of the second mover assembly 244. FIG. 3E illustrates that thesecond stage 240 includes one or more balance weights 370A, and one ormore stops 370B that are fixedly secured to the table 362. The balanceweights 370A are used to adjust the center of gravity (not shown) of thesecond stage 240. Accordingly, the number and location of the balanceweights 370A can be varied to achieve the desired center of gravity. Inone embodiment, one or more fasteners (not shown) are used toselectively each of the balance weights 370A and the stops 370B to thetable 362.

The stops 370B provide a safe contact area for the second stage 240.With this design, when the Z movers 255 (not shown in FIG. 3E) areturned off, the stops 370B can engage the first stage 238 (not shown inFIG. 3E) to support the second stage 240. The design and number of thestops 370B can vary. In FIG. 3E, the second stage 240 includes threespaced apart, generally rectangular shaped stops 370B.

FIG. 3E illustrates that the left side of the table 362 defines acantilevering, second necked region 372A that defines a second mountingsurface 372B that is substantially opposite from the first mountingsurface 366B. The first mounting surface 366B has a first surface length366C and a first surface area. Similarly, the second mounting surface372B has a second surface length 372C and a second surface area. Incertain designs, the surface lengths 366C, 372C and the surface areasare relatively small. In alternative, non-exclusive embodiments, eachsurface length 366C, 372C is less than approximately 10, 20, 30, 40, 50or 100 mm. Further, in alternative, non-exclusive embodiments, eachsurface area is less than approximately 5, 10, 20, 30, 40, or 50 cm².

A mover mounting surface 368D of the mover housing 368A of each X mover252F, 252S has a housing length 368E and an attachment side area. Inalternative, non-exclusive embodiments, each housing length 368E isgreater than approximately 30, 50, 70, 100, 125, 150, 175, or 200 mm.Further, in alternative, non-exclusive embodiments, each attachment sidearea is greater than approximately 10, 20, 40, 50, 75, or 100 cm².

In certain embodiments, the housing length 368E of the second X mover252S is greater than the second surface length 372C and the housing sidearea is greater than the surface area of the second mounting surface372B. In alternative, non-exclusive embodiments, the housing length 368Eof the second X mover 252S is at least approximately 20, 40, 60, 80,100, 150, 200, 250, 300, 350, 400, 450, or 500 percent longer than thesecond surface length 372C. Further, in alternative, non-exclusiveembodiments, the housing side area of the second X mover 252S is atleast approximately 20, 40, 60, 80, 100, 200, 300, 400, 500, 600, 700,800, 900, or 1000 percent larger than the surface area of the secondmounting surface 372B. With this design, the second mover component 256Bof the second X mover 252S cantilevers away from the second neckedregion 372A of the table 362.

It should be noted that temperature changes in the second movercomponent 256B of the second X mover 252S can cause deformation, e.g. achange in length or bending of the second mover component 256B. Thetemperature changes can be caused by heat from the coils of the second Xmover 252S, and thermal radiation. Because of the relatively smallsecond surface length 372C, and the gap between the second movercomponent 256B and the second necked region 372A of the table 362, theeffects of deformation of the second mover component 256B are reduced.

Somewhat similarly, a mover mounting surface 368F of the mountingbracket 368C has a bracket length 368G and a bracket surface area. Inalternative, non-exclusive embodiments, the bracket length 368G isgreater than approximately 50, 100, 150, 200, 250, or 300 mm. Further,in alternative, non-exclusive embodiments, the bracket surface area isgreater than approximately 10, 20, 40, 60, 80, 100, 120, or 150 cm².

In certain embodiments, the bracket length 368G is greater than thesurface length 366C of the first mounting surface 366B and the bracketsurface area is greater than the surface area of the first mountingsurface 366B. In alternative, non-exclusive embodiments, the bracketlength 368G is at least approximately 20, 40, 60, 80, 100, 150, 200,250, 300, 350, 400, 450, or 500 percent longer than the surface length366C of the first mounting surface 366B. Further, in alternative,non-exclusive embodiments, the bracket surface area is at leastapproximately 20, 40, 60, 80, 100, 200, 300, 400, 500, 600, 700, 800,900, or 1000 percent bigger than the surface area of the first mountingsurface 366B. With this design, the mounting bracket 368C with thesecond mover component 256B of the movers 252F, 254F, 254S cantileveraway from the first necked region 366A of the table 362.

It should be noted that temperature changes in the second movercomponent 256B of the first X mover 252F and the Y movers 254F, 254S cancause deformation, e.g. bending of the mounting bracket 368C. Because ofthe relatively small first surface length 366C, effects of deformationof the mounting bracket 368C are reduced.

In one embodiment, the second stage 240 also includes (i) a firstfastener assembly 373A for selectively securing the mounting bracket368C with the second mover components 256B of the first X mover 252F andthe Y movers 254F, 254S to the first mounting surface 366B, and (ii) asecond fastener assembly 373B (illustrated in phantom) for selectivelysecuring the mover housing 368A of the second X mover 252S to the secondmounting surface 372B. In FIG. 3B, each fastener assembly 373A, 373Bincludes four fasteners 373C that can be selectively threaded into thetable 362 at the respective mounting surfaces 366B, 372B. Alternatively,each fastener assembly 373A, 373B can include more than four or lessthan four fasteners 373C. With this design, the second mover components256B of the X movers 252F, 252S and the Y movers 254F, 254S can beeasily replaced. This leads to a modular type design where differenttypes of movers can be readily changed on the stage assembly. Stated inanother fashion, with this design, the movers of the second moverassembly 224 can easily be reconfigured.

It should be noted that in one embodiment, the second mover component256A of the first X mover 252F is positioned above the center of gravityof the second stage 240 and the and the second mover component 256A ofthe second X mover 252S is positioned below the center of gravity of thesecond stage 240. Further, the X movers 252F, 252S are positioned todirect a net force through the center of gravity of the second stage240.

FIG. 3E also illustrates that the table 362 includes one or more tablepads 374A that interact with the stage bearing assembly 257 (illustratedin FIG. 2D). The number, location, size and shape of table pads 374A canvary. In this embodiment, the table 362 includes three spaced aparttable pads 374A. Further, each table pad 374A is generally hollow diskshaped and includes a generally flat bearing surface 374B that faces theZ movers 255.

FIG. 3F is a simplified illustration of a portion of the table 362 and aportion of the second mover components 256B of the second mover assembly244. In this illustration, many of the surface features of the table 362have been removed. In particular, this illustration highlights the firstnecked region 366A and the second necked region 372A of the table 362.

FIG. 3F also illustrates that the second mover component 256B of thefirst X mover 252F, and the Y movers 254F, 254S are secured to the rightside of the table 362, and the second mover component 256B of the secondX mover 252S is secured to the left side of the table 362. The mountingbracket 368C secures the mover housing 368A of the first X mover 252F,and the Y movers 254F, 254S to the table 362.

FIG. 3F also highlights the relationship between (i) the first surfacelength 366C of the first mounting surface 366B and the bracket length368G of the mounting bracket 368C, and (ii) the second surface length372C of the second mounting surface 372B and the housing length 368E ofthe mover mounting surface 368D.

FIG. 3G is a perspective view of the second mover component 256B of oneof the X movers 252F, 252S including the mover housing 368A and thespaced apart magnet arrays 368B. In this embodiment, each of the magnetarrays 368B includes a plurality of magnets 376B that each has atriangular shaped cross-section. Moreover, the mover housing 368A can bemade of a ceramic material.

FIGS. 3H and 3I are alternative, exploded perspective views of oneembodiment of the table 362. In this embodiment, the table 362 includesan upper first table section 378A, an intermediate second table section378B that is fixedly secured to the bottom of the first table section378A, and a lower third table section 378C that is fixedly secured tothe bottom of the second table section 378B. Alternatively, the table362 could be designed with fewer than three or more than three tablesections. With this design, the sections of the table 362 can bedesigned to achieve the desired characteristics of the table 362.

The design of each table section 378A, 378B, 378C can vary. In FIGS. 3Hand 3I, the first table section 378A includes a generally flat plateshaped upper plate 380A. The second table section 378B includes agenerally flat plate shaped intermediate plate 380B and a plurality ofintermediate walls 380C that extend transversely to and cantileverupward from the intermediate plate 380B. Somewhat similarly, the thirdtable section 378C includes a generally flat plate shaped lower plate380D and a plurality of lower walls 380E that extend transversely to andcantilever upward from the lower plate 380D.

The shape, positioning, and number of walls 380C, 380E can be varied toachieve the desired stiffness, weight, and vibration characteristics ofthe table 362. In this embodiment, the intermediate walls 380C includean outer rectangular shaped perimeter wall 382A, two, coaxial tubularshaped walls 382B, a plurality of radial walls 382C that extend radiallyfrom the inner ring towards the outer perimeter, and three, spaced apartcross-brace walls 382D. Somewhat similarly, in this embodiment, thelower walls 380E include an outer rectangular shaped perimeter wall384A, two, coaxial tubular shaped walls 384B, a plurality of radialwalls 384C that extend radially from the inner ring towards the outerperimeter, and three, spaced apart cross-brace walls 384D.

In certain non-exclusive embodiments, one or more of the walls has athickness of approximately 1, 2, 5, 7, 10, 15 or 20 mm.

The table sections 378A, 378B, 378C can be fixed together with anadhesive, fasteners, welds, brazing, or other suitable fashion. In oneembodiment, at least one of the table sections 378A, 378B, 378C is madeof a ceramic material. With the sections 378A, 378B, 378C securedtogether, the table 362 defines a plurality of spaced apart cavities.

In should be noted that the table 362 illustrated in FIGS. 3H and 3I isa box type structure that includes a plurality of walls that arepositioned therein to provide a lightweight table 362 that is verystiff. This table 362 also includes an aperture 386 that facilitatesreplacement of the work piece.

In one embodiment, the table 362 is approximately 350 mm by 450 mm by 40mm thick. Further, in alternative non-exclusive embodiments, the table362 has a mass of less than approximately 7, 6.5, 6, 5.8, 5.5 or 5 kg.Moreover, in alternative non-exclusive embodiments, the table 362 has afirst vibration frequency of at least approximately 500, 600, 700, 800,or 1000 HZ.

FIG. 3J is an exploded perspective view of yet another embodiment of atable 362J. In this embodiment, the table 362J includes an upper firsttable section 378AJ, an intermediate second table section 378BJ that isfixedly secured to the bottom of the first table section 378AJ, and alower third table section 378CJ that is fixedly secured to the bottom ofthe second table section 378BJ. Alternatively, the table 362J could bedesigned with fewer than three or more than three table sections.

In FIG. 3J, the first table section 378AJ includes a generally flatplate shaped upper plate 380AJ. The second table section 378BJ includesa generally flat plate shaped intermediate plate 380BJ and a pluralityof intermediate walls 380CJ that extend transversely to and cantileverupward from the intermediate plate 380BJ. Somewhat similarly, the thirdtable section 378CJ includes a generally flat plate shaped lower plate380DJ and a plurality of lower walls 380EJ that extend transversely toand cantilever upward from the lower plate 380DJ.

In this embodiment, the intermediate walls 380CJ include an outerperimeter wall 382AJ, and a tubular shaped inner wall 382BJ. Somewhatsimilarly, in this embodiment, the lower wall 380EJ includes an outerperimeter wall 384AJ and a tubular shaped inner wall 384BJ.

In one embodiment, one or more of the table sections 378AJ, 378BJ, 378CJincludes a honeycomb type structure 371J and/or a foam material 373J. InFIG. 3J, the intermediate second table section 378BJ includes ahoneycomb type structure 371J positioned between the intermediate walls380CJ, and the lower third table section 378CJ includes a foam material373J positioned between the lower walls 380EJ. Examples of a honeycombtype structure 371J includes a plurality of very thin walls that can bemade of a number of materials such as aluminum, cardboard, fiberreinforced plastic. Examples of a foam material 373J include a polymerfoam.

FIG. 4A is a perspective view of one embodiment of a Z mover 255suitable for use with the present invention. In this embodiment, the Zmover 255 includes a Z output assembly 400, a Z frame 402, Z bearing 404(illustrated as arrows), a Z measurer 406, the first mover component256A and the second mover component 256B (illustrated in FIG. 4B). Thedesign of each of these components can be varied to suit the designrequirements of the Z mover 255.

The Z output assembly 400 is moved relative to the Z frame 402 along theZ axis. In one embodiment, the Z output assembly 400 includes a Z beam408, a Z dampener 410, a Z housing 412, one or more housing supports414, a Z mover output 416, and a connector assembly 418. In FIG. 4A, theZ beam 408 is rigid and extends through a portion of the Z frame 402.The Z beam 408 also supports a portion of the second mover component256B.

The Z dampener 410 is secured to the bottom of the Z beam 408 andsecures the bottom of the Z beam 408 to the Z frame 402. In oneembodiment, the Z dampener 410 supports the weight of the Z beam 408,allows the Z beam 408 to move relative to the Z frame 402, and inhibitsvibration (including along the Z axis) from the first stage (not shownin FIG. 4A) from being transmitted to the Z beam 408 and the secondstage (not shown in FIG. 4A). As a result thereof, the Z mover 255 has arelatively low transmissibility of vibration. Stated in another fashion,the Z dampener 410 can reduce the level of vibration that wouldotherwise be transferred from the first stage to the second stage. Inalternative, non-exclusive embodiments, the Z dampener 410 can reducethe level of vibration that would otherwise be transferred to the secondstage by at least approximately 1, 5, 10, 20, 30, 40, 50, 60, 70, 80,90, 99 or 100 percent.

The Z housing 412 supports a portion of the second mover component 256B.In FIG. 4A, the Z housing 412 includes a flat top section 420 and anannular cylindrical section 422. In one embodiment, the Z housing 412encircles the mover components 256A, 256B.

The one or more housing supports 414 connect the Z housing 412 to the Zbeam 408 and allow a portion the first mover component 256A to extendbelow the Z housing 412 and be secured to the top of the Z frame 402.

The Z mover output 416 is generally flat disk shaped and includes agenerally flat, top bearing surface 424 that faces the table (not shownin FIG. 4A).

The connector assembly 418 mechanically and flexibly connects the bottomof the Z mover output 416 to the top of the Z housing 412. As a resultthereof, movement of the Z housing 412 along the Z axis results inmovement of the Z mover output 416. The design of the connector assembly418 can be varied pursuant to the teachings provided herein. In oneembodiment, the connector assembly 418 includes a flexure that extendsbetween the Z mover output 416 and the Z housing 412. As used herein,the term “flexure” shall mean a part that has relatively high stiffnessin some directions and relatively low stiffness in other directions. InFIG. 4A, the flexure has (i) a relatively high stiffness along the X, Yand Z axes and about the Z axis and (ii) is relatively flexible about Xand Y axes. The ratio of relatively high stiffness to relatively lowstiffness is at least approximately 100/1, and can be at leastapproximately 1000/1.

With this design, movement of the Z housing 412 along the Z axis resultsin movement of the Z mover output 416 along the Z axis. However, theconnector assembly 418 allows the Z mover output 416 to tilt and pivotabout the X axis and about the Y axis relative to the Z housing 412. Itshould be noted that other designs for the connector assembly 418 can beutilized.

The Z frame 402 supports the Z output assembly 400 and supports thefirst mover component 256A. The size, shape and design of the Z frame402 can be varied. In FIG. 4A, the Z frame 402 is generally “E” shapedand includes an upper bar section 426A, a lower bar section 426B, anintermediate bar section 426C positioned between the upper bar section426A and the lower bar section 426B and a rear bar section 426D thatconnects upper, intermediate, and lower bar sections 426A, 426B, 426Ctogether. In FIG. 4A, the upper bar section 426A and the intermediatebar section 426C include an aperture 426E for receiving the Z beam 408and the lower bar section 426B includes a slot 426F for receiving aportion of the Z beam 408. Moreover, the upper bar section 426A and theintermediate bar section 426C each include a selectively removablesection 428 that facilitates placement of Z beam 408 in the Z frame 402.

The lower bar section 426B is fixedly secured to the top of the firststage 238. Further, the first mover component 256A is fixedly secured tothe upper bar section 426A.

The Z bearing 404 guides the movement of the Z beam 408 relative to theZ frame 402. In one embodiment, the Z bearing 404 allows for themovement of the Z beam 408 along the Z axis (pure vertical movement) andinhibits movement of the Z beam 408 relative to the Z frame 402 and thefirst stage along the X and Y axes, and about the X and Y axes. In oneembodiment, the Z bearing 404 is a non contact type bearing, such as afluid type bearing, or a magnetic type bearing between the intermediatebar section 426C and the Z beam 408. With the non contact type bearing,the Z beam 408 can be moved along the Z-axis with little to no friction.

The Z measurer 406 measures the movement of the Z beam 408 relative tothe Z frame 402. The Z measurer 406 detects position of the Z beam 408relative to the Z frame 402 (the first stage 238) in the Z direction. Inone embodiment, this information substantially corresponds to themovement (extension and shrinkage) of the Z dampener 410 such as an airbellows along the Z axis. In the embodiment illustrated in FIG. 4A, theZ measurer 406 is a linear encoder. Information regarding the movementof the Z beam 408 can be directed to the control system 24 (illustratedin FIG. 1) so that the control system 24 can control the Z mover 255.Alternatively, for example, the Z measurer 406 can be a capacitancegauge or another type of sensor.

Additionally, as discussed in more detail below, in certain designs,information from the Z measurer 406 can be used to reduce the level ofvibration that is being transferred from the first stage to the secondstage. Moreover, in certain designs, information from the Z measurer 406can be used in the initialization of the measurement system.

FIG. 4B is a cut-away perspective view and FIG. 4C is a cut-away planview of the Z output assembly 400 and the second mover component 256B.In this embodiment, the Z beam 408 is generally tubular shaped.

In FIGS. 4B and 4C, the Z dampener 410 is a fluid bellows that includes(i) a top that is secured to the bottom of the Z beam 408 and (ii) abottom that is fixedly secured to the Z frame 402 (illustrated in FIG.4A). With this design, the Z dampener 410 inhibits rotation of the Zoutput assembly 400 about the Z axis. The pressure of the fluid in thefluid bellows can be adjusted to suit the needs of the Z dampener 410.In one embodiment, the fluid pressure is set in the fluid bellows andnot changed. Alternatively, for example, the fluid pressure could beadjusted and controlled with a fluid source (not shown). In yet anotherembodiment, the Z dampener 410 can be a spring or another type ofdamping device.

FIGS. 4B and 4C also illustrate the second mover component 256B in moredetail. In this embodiment, the second mover component 256B includes atubular shaped outer magnet 430A that is secured to the inside of the Zhousing 412, and a spaced apart, coaxial tubular shaped inner magnet430B. The bottom of the inner magnet 430B is secured to the top of the Zbeam 408 and the top of the inner magnet 430B is secured to the bottomof the top section 420 of the Z housing 412.

FIGS. 4B and 4C also illustrate that the housing supports 414 extendbetween the top of the Z beam 408 and the bottom of the Z housing 412.

FIG. 4D is an enlarged, cut-away view of a portion of the Z outputassembly 400, the first mover component 256A and the second movercomponent 256B. In this embodiment, the first mover component 256Aincludes a tubular shaped coil 432A that is positioned between andcoaxial with the magnets 430A, 430B, and a plurality of spaced apartfeet 432B that extend downward from the coil 432A between the spacedapart housing supports 414. The feet 432B are used for fixedly securingthe coil 432A to the Z frame (not shown in FIG. 4D). With this design,current to the coil 432A causes the magnets 430A, 430B and the Z outputassembly 400 to move along the Z axis. Arrows 433 illustrate theorientation of the magnets.

FIG. 4D also illustrates the flexure 418 in more detail. Morespecifically, in this embodiment, the flexure 418 includes (i) an upperdisk shaped region 434A that is secured to the bottom of the Z moveroutput 416, (ii) a lower disk shaped region 434B that is secured to thetop of the Z housing 412, and (iii) a pair of spaced apart flexibleconnector strips 434C that connect the regions 434A, 434B together.

FIG. 5 is a simplified illustration of the relationship between thesecond stage 240, a portion of the three Z movers 255, and the stagebearing assembly 257 (illustrated as arrows) with the second stage 240tilted. In particular, FIG. 5 illustrates that (i) each of table pads376A is aligned with the mover output 416 of one of the Z movers 255,(ii) the stage bearing assembly 257 maintains the table pads 376A spacedapart from the mover outputs 416, and (iii) the connector assembly 418allows each of the mover outputs 416 to pivot relative to the rest ofthe Z mover 255. As a result thereof, the mover outputs 416 pivot sothat the bearing surface 374B of the table pads 376A is substantiallyparallel with the bearing surface 424 of the mover output 416 duringpivoting of the second stage 240. It should be noted that the pure Zmotion from the Z movers 255 along the Z axis can be used to tilt thesecond stage 240.

FIG. 6A is a top perspective view and FIG. 6B is a bottom perspectiveview of a second stage 640 with another embodiment of the second moverassembly 644. The second mover assembly 644 includes a first X mover652F, a second X mover 652S, a first Y mover 654F, and a second Y mover654S. In this embodiment, the second stage 640 is similar to the secondstage 240 described above. However, in this embodiment, the X and Ymovers 652F, 652S, 654F, 654S of the second mover assembly 644 aredifferent.

In this embodiment, each of the X and Y movers 652F, 652S, 654F, 654S isan attraction only type actuator, such as an E-I Core actuator. Anexample of the E-I core actuator is described in U.S. Pat. No.6,069,471, which is incorporated herein by reference in its entirety. Inthis embodiment, each of the first mover components 656A includes a pairof E cores and tubular conductors that are secured to the first stage(not shown in FIGS. 6A and 6B) and the second mover component 656B is anI core that is secured to the second stage 640.

It should be noted that the X and Y movers 652F, 652S, 654F, 654S aresecured to the second stage 640 in a fashion that is similar to how theX and Y movers 252F, 252S, 254F, 254S are secured to the second stage240 described above. This allows for a stage assembly that can readilybe reconfigured with different types of movers.

FIG. 7A is a top perspective view and FIG. 7B is a side perspective viewof a second stage 740 with another embodiment of the second moverassembly 744. In this embodiment, the second stage 740 is similar to thesecond stage 240 described above. However, in this embodiment, thesecond mover assembly 744 includes a first pair of X movers 752F (onlyone is shown), a second pair of X movers 753F (only one is shown), afirst Y movers 754F, and a second pair of Y movers 755F, 755S.

In this embodiment, (i) each of the X movers 752F of the first pair isan E-I core actuator, (ii) each of the X movers 753F of the second pairis a voice coil motor, (iii) the Y mover 754F is an E-I core actuator,and (iv) each of the Y movers 755F, 755S of the second pair is a voicecoil motor. With this design, for example, (i) the first pair of Xmovers 752F can be used for rapid, coarse movements of the second stage740 along the X axis, (ii) the second pair of X movers 753F can be usedfor fine movements of the second stage 740 along the X axis, (iii) the Ymover 754F can be used for rapid, coarse movements of the second stage740 along the Y axis, and (iv) the second pair of Y movers 755F, 755Scan be used for fine movements of the second stage 740 along the Y axisand about the Z axis.

It should be noted that the X and Y movers 752F, 753F, 754F, 755F, 755Sare secured to the second stage 740 in a fashion that is similar to howthe X and Y movers 252F, 252S, 254F, 254S are secured to the secondstage 240 described above. This allows for a stage assembly that canreadily be reconfigured.

FIG. 8 is a simplified illustration of (i) a work piece 800, (ii) asecond stage 840 including a table 862, a chuck 864, and three tablepads 874A, (iii) a Z mover output 816 of the three Z movers 855, and(iv) a stage bearing assembly 857. More specifically, FIG. 8 illustratesone embodiment of how a fluid at a pressure that is different thanatmospheric pressure, e.g. a low pressure or a vacuum, from a fluidsource 811 can be transferred from the fluid source 811 to the chuck864.

In this embodiment, the stage bearing assembly 857 is vacuum preloadedfluid bearing. Further, two of the table pads 874A include an inlet port813 that is in fluid communication with the chuck 864 via stage channels815, 818 (illustrated in phantom). In one embodiment, each mover output816 includes an outlet port 817 that is in fluid communication with thefluid source 811 and supplies vacuum to the stage bearing assembly 857.

With this design, the inlet port 813 is part of and moves with thesecond stage 840 and the outlet port 817 moves with the first stage. Asa result thereof, the inlet port 813 is moved with six degrees of motionrelative to the outlet port 817. Moreover, with this design, a portionof the vacuum created by the fluid source 811 to create the vacuumpreloaded fluid bearing 857 can be diverted into table 862. Vacuumsupplied by the stage channel 815 is directed to the chuck 864 to createthe vacuum used by the chuck 864 to retain the work piece 800 to thechuck 864. Further, vacuum supplied by the stage channel 818 is directedthrough the table 862 to the chuck 864 to create the vacuum to retainthe chuck 864 to the second stage 840. Further, with this design, thevacuum source 811 can be connected to the chuck 864 without a hose thatextends from the fluid (vacuum) source 811 to the chuck 864. It shouldbe noted that no fluid conduit, e.g. a hose or tube, extends between theinlet ports 813 and the outlet ports 817.

FIG. 9A is a simplified illustration of a portion of the stage assembly220 illustrated in FIGS. 2A-4D, including the first stage 238, thesecond stage 240, and the Z movers 255. In FIG. 9A, the Z outputassembly 400, the Z frame 402, the Z measurer 406, the first movercomponent 256A and the second mover component 256B of each Z mover 255is represented therein. Further, in FIG. 9A, the Z beam 408, the Zdampener 410, and the Z mover output 416 of each Z output assembly 400is represented therein.

As discussed above, the Z dampener 410 is secured to the bottom of the Zbeam 408 and couples the bottom of the Z beam 408 to the first stage238. In one embodiment, the Z dampener 410 supports the weight of the Zbeam 408 and of the second stage 240, allows the Z beam 408 to moverelative to the first stage 238, and reduces the level of vibration fromthe first stage 238 that is being transmitted to the Z beam 408 and thesecond stage 240. It should be noted that each of the Z dampeners 410has a stiffness. In non-exclusive embodiments, for example, each Zdampener 410 can have a stiffness (K) along the Z axis of approximately0.1, 0.5, 1, 2, 5, 10, 15 or 20 N/mm.

As a result of the stiffness of the dampener 410, disturbances from theground or environment that are transferred to the first stage 238 canstill be at least partly transmitted to the second stage 240 via thedampener 410.

For each Z mover 255, the Z measurer 406 measures the movement and/orposition of the Z beam 408 and a portion of the Z dampener 410 (e.g. thetop) relative to the first stage 238 or some other reference. Asdiscussed below, information regarding the movement of the Z beams 408can be transferred to the control system 24 (illustrated in FIG. 1) sothat the control system 24 can control the Z movers 255 to compensatefor the stiffness and damping of the Z dampeners 410.

In certain embodiments, disturbances (e.g. from the ground orenvironment) that are transferred to the first stage 238 can cause adisturbance movement of the first stage 238 along the X, Y and Z axesand about the X, Y and Z axes. With the dampeners 410 illustrated inFIG. 9A, (i) the disturbance movement of the first stage 238 along the Xand Y axes and about the Z axis is not transferred to the second stage240, and (ii) the disturbance movement of the first stage 238 along theZ axis and about the X and Y axes results in a smaller displacement of aportion of the dampeners 410 and the Z beams 408 along the Z axis. The Zmeasurers 406 can be used to measure this displacement. Further, withthis information, the velocity of that displacement can be calculated.As discussed below, using the displacement and velocity information, thecontrol system 24 can control the Z movers 255 to compensate for thedisturbances that are transferred through the dampeners 410.

In one embodiment, if the Z measurers 406 determine that movement of thefirst stage 238 has caused the Z beams 408 to move upward a displacement+d at a velocity of +v, the control system can direct power at theappropriate rates to the first mover components 256A to create downwardforces on the Z beams 408 to counteract, correct and/or reduce undesiredupward displacement of the Z beams 408. Similarly, if the Z measurers406 determine that movement of the first stage 238 has caused the Zbeams 408 to move downward a displacement −d at a velocity of −v, thecontrol system 24 can direct power at the appropriate rates to the firstmover components 256A to create upward forces on the Z beams 408 tocounteract, correct and/or reduce undesired downward displacement of theZ beams 408. If the event that undesired displacement is entirelycounteracted, the second stage 240 is isolated from the disturbancemovement of the first stage 238.

FIG. 9B is a simplified block diagram that illustrates the control ofthe Z movers 255 of the second mover assembly 244 to precisely positionthe second stage 240 along the Z axis and about the X and Y axes. Inthis embodiment, the desired position of the second stage 240 is input921 into the system. The desired position is compared with a sensorsignal vector S of the second stage 240 that is generated by themeasurement system 22. A difference vector is determined by comparingthe input 921 to the sensor signal vector S. A control system 922(control system 22) determines the power that is directed to the Zmovers 255 to precisely position the second stage 240 along the Z axis.

In one embodiment, the control system 922 includes (i) a positioningsystem 923 that calculates the amount of power to be directed to the Zmovers 255 needed to position the second stage 240, and (ii) acompensation system 925 that calculates the amount of power to bedirected to the Z movers 255 needed to compensate for at least a portionof the stiffness and damping of the Z dampeners 410 and/or to reduce atleast a portion of the level of vibration that is transmitted from thefirst stage 238 to the second stage 240 via the Z dampeners 410. Thecontrol system 922 can include PID (proportional integral derivative)controller, proportional gain controller or a lead-lag filter, or othercommonly known law in the art of control, for example.

The power directed to the Z movers 255 creates a total mover force F_(M)that is directed at the second stage 240. In one embodiment, the totalmover force includes a servo force component F_(S) and a compensationforce component F_(C). The servo force component F_(S) is directed tothe second stage 240 to position the second stage 240. The compensationforce component F_(C) is directed to the second stage 240 to offsetand/or compensate for at least a portion of the stiffness of the Zdampener 410 and/or to reduce at least a portion of the level ofvibration that is transmitted from the first stage 238 to the secondstage 240 via the Z dampeners 410. Stated in another fashion, thecompensation force component F_(C) contains negative stiffness andnegative damping terms to counteract the disturbance force F_(D) (notshown) that is transferred from the first stage 238 through Z dampeners410. When the compensation force component F_(C) is approximately equaland opposite to the disturbance force F_(D), the disturbance iscounteracted and compensated for. In alternative, non-exclusiveembodiments, the absolute value of the compensation force componentF_(C) is at least approximately 10, 20, 40, 50, 70, 80, 90, 99, 100, or110 percent of the absolute value of the disturbance force F_(D).

In certain designs, the performance of the Z movers 255 is relativelygood, and the Z movers 255 have a stable, repeatable, linear stiffness,which can be canceled by the compensation force component F_(C). Inalternative, non-exclusive embodiments, the compensation force componentF_(C) is able to reduce the level of disturbance and/or vibration thatwould otherwise be is transmitted from the first stage 238 to the secondstage 240 via the Z dampeners 410 by at least approximately 1, 5, 10,20, 30, 40, 50, 60, 70, 80, 90, 99 or 100 percent.

For a one degree of freedom system, the dynamics of the movement of thesecond stage 240 relative to the first stage 238 can be summarized withthe following equation:Ma+Cv+Kd=F  equation (1)

Where M is the mass of the second stage 240, C represents the damping ofthe Z dampener 410, K represents the stiffness of the Z dampener 410, Fis the force being imparted upon the second stage 240 along the one axis(e.g. the Z axis), a is the acceleration, v is velocity and d isdisplacement. When the information of the displacement and velocity isavailable, the Z movers 255 can be used to compensate for the stiffness(K) and damping (C) of the Z dampener 410. The information regarding thedisplacement and velocity of the Z beam 408 can be measured by the Zmeasurer 406.If F=Cv+Kd+u  equation (2)

Where u is the servo Force component F_(S) (the desired force).Combining equation (1) with equation (2) results in the followingequation:Ma=u  equation (3)

In one embodiment, it is desired that the displacement d to follow atrajectory command r, then u should be set as Ma:Ma−Ma=0  equation (4)

Therefore, d should follow r.

For a more general 6 degree of movement system, the same techniques ascan be utilized as for the one degree of movement system. The 6 degreeof movement system dynamics can be written in the matrix form.[M]qa−[C]qv+[K]qd=F   equation (5)

Once the stiffness and damping matrices [K] and (C] for the system arecalculated, the actuator forces needed to compensate for them can becalculated.F=[C]qv+[K]qd+u   equation (6)

Equations (5) and (6) are in same form as equations (1) and (2).Accordingly, the same goal can be achieved in a 6 degree of movementsystem by using more generalized vectors and matrices.

Simulated tests results were performed on a stage assembly that includesa first stage and a second stage. FIGS. 9C-9E are graphs that illustratethe simulated test results for transmissibility along the Z, along theX, and along the Y axis, respectively. Transmissibility is defined asthe ratio of the displacement between the first stage and second stageacross different frequencies. The simulation results show that thetransmissibility dramatically reduced with the stiffness and dampingcompensation. FIGS. 9C to 9E illustrate Bode plots of transmissibilitybetween the first stage and the second stage produced by a 6 degree offreedom simulation. If one hundred percent of the vibration istransmitted from the first stage to the second stage, the magnitude ofthe transmissibility would be 1.0, or 0 dB (on the top plot of each ofFIGS. 9C-9E). To improve the positioning accuracy of the second stage,disturbances from the first stage are inhibited from being transferredto the second stage. In other words, the transmissibility is made assmall as possible (a negative number in the magnitude (top) plot inFIGS. 9C-9E.)

FIGS. 9C-9E compare the transmissibility between two cases. Thebenchmark case (dashed line) is the performance when stiffness anddamping compensation is not used. When compensation is active (thecompensation case is illustrated with a solid line), the magnitude ofthe transmissibility is reduced, especially in low frequencies. In FIGS.9C-9E, X can have a value of 1, 2, 5, 10, 20, 50 or 100 dB.

In one embodiment, the stiffness of each of the Z movers can beexperimentally measured by controlling the Z movers to slowly move thesecond stage up and down. The measured stiffness can be used by thecontrol system to quickly calculate the appropriate compensation forceF_(c). In one embodiment, for example, the second stage is moved up anddown within a range of approximately 2 mm in approximately 0.5 seconds.

FIG. 9F is a graph that illustrates the test results for the total forceapplied by the Z movers versus the position of the second stage during aslow movement of the second stage with the Z movers. In FIG. 9F, line931 represents the linear stiffness, which is the sum of the threestiffnesses of the three Z movers. In this embodiment, the stiffness isapproximately 9 N/mm.

FIG. 9G is a graph that illustrates the effect of stiffness compensationfor control to the Z movers. In FIG. 9G, line 933 represents the totalstiffness acting on the center of gravity of the second stage. In thisembodiment, the total stiffness acting on the second stage has beenreduced to approximately 50 N/m.

FIG. 10A is a simplified top perspective view of a portion of a stageassembly 1020A having features of the present invention. For example,the stage assembly 1020A can be used as the wafer stage assembly 20 orthe reticle stage assembly 18 in the exposure apparatus 10 of FIG. 1.Alternatively, the stage assembly 1020A can be used to move other typesof devices.

The components of the stage assembly 1020A that are illustrated in FIG.10A include a first stage 1038A, a second stage 1040A, a measurementsystem 1022A and an initialization system 1081A (illustrated inphantom). The stages 1038A, 1040A can be similar in design to thecorresponding designs described above. The first mover assembly and thesecond mover assembly of the stage assembly 1020A are not illustrated inFIG. 10A. The mover assemblies can be similar to the correspondingcomponents described above and illustrated in FIGS. 2A-4D. For example,the first mover assembly can be used to move the first stage 1038A alongthe X and Y axes and about the Z axis, and the second mover assembly canbe used to move the second stage 1040A along the X, Y, and Z axes andabout the X, Y, and Z axes. Alternatively, for example, the first moverassembly can be designed to move the first stage 1038A with more thanthree or less than three degrees of movement and/or the second moverassembly can be used to move the second stage 1040A with less than sixdegrees of movement.

The measurement system 1022A constantly monitors the position of thesecond stage 1040A. With this information, the second mover assembly canbe controlled to precisely position the second stage 1040A. The designof the measurement system 1022A can vary according to the degrees ofmovement of the second stage 1040A. For example, the measurement system1022A can measure the position of the second stage 1040A along at leastone axis and/or about at least one axis and can utilize multiple laserinterferometers, encoders, and/or other measuring devices.

In the embodiment illustrated in FIG. 10A, the measurement system 1022Aincludes six interferometer systems 1023A-1023C that cooperate tomonitor the position of the second stage 1040A along three axes andabout three axes. More specifically, in this embodiment, the measurementsystem 1022A includes (i) three spaced apart Z interferometer systems1023A that cooperate to measure the position of the second stage 1040Aalong the Z axis, about the X axis and about the Y axis, (ii) two Xinterferometer systems 1023B that cooperate to measure the position ofthe second stage 1040A along the X axis and about the Z axis, and (iii)a Y interferometer system 1023C that measures the position of the secondstage 1040A along the Y axis. In this embodiment, each interferometersystem 1023A-1023C includes a first interferometer component 1025A thatis positioned away from the second stage 1040A and a secondinterferometer component 1025B that is secured to the second stage 1040Aand that moves with the second stage 1040A. The exact location of theinterferometer components 1025A, 1025B can be varied to achieve thedesired performance characteristics of the stage assembly 1020A.

In the embodiment illustrated in FIG. 10A, (i) each first interferometercomponent 1025A is an interferometer block that directs a laser beam1027 at the second interferometer component 1025B and that receives thebeam that is reflected off of the second interferometer component, and(ii) each second interferometer component 1025B is a reflector, e.g. amirror. Alternatively, the first interferometer component can includethe reflector while the second interferometer component can include theinterferometer block. A suitable laser interferometer is sold byAgilent, located in Santa Clara, Calif.

In certain embodiments, the mechanical range of motion of the secondstage 1040A about the X, Y and Z axes is much greater than the workingrange of one or more of the interferometer systems 1023A-1023C. Statedin another fashion, one or more of the interferometer systems1023A-1023C can have a limited rotational working range. For example,for each interferometer system 1023A-1023C to function properly, thebeam 1027 from the interferometer block must be reflected back to theinterferometer block from the reflector (second interferometercomponent). If the angle of the reflector is not within the limitedrotational working range, the beam will not be reflected back to theinterferometer block. In one embodiment, each Z interferometer system1023A has a FA working range, each X interferometer system 1023B has aSA working range, and the Y interferometer system 1023C has a TA workingrange.

The size of each limited rotational working range can vary according tothe type of interferometer system 1023A-1023C. For example, in one typeof interferometer system 1023A-1023C, in order to function properly, thereflector must be at a 90 degree angle plus or minus 0.06 degreesrelative to the beam 1027. In this design, the working range isapproximately 0.12 degrees. In alternative, non-exclusive embodiments,the working range is approximately 0.01, 0.05, 0.1, or 0.5 degrees.

When power is initially applied to the stage assembly 1020A, the secondstage 1040A is usually in an unknown orientation, and the one or more ofthe interferometer systems 1023A-1023C may not be operational becausethe second stage 1040A is rotated outside of the working range. Forexample, if the second stage 1040A is rotated about the X axis or the Yaxis an amount that is greater than the FA working range, the Zinterferometer systems 1023A will not function. Somewhat similarly, ifthe second stage 1040A is rotated about the Z axis an amount that isgreater than the SA working range and the TA working range, the X and Yinterferometer systems 1023B, 1023C will not function.

In this design, the initialization system 1081A provides a way to getthe second stage 1040A aligned in the correct orientation when theinterferometer systems 1023A-1023C are not operational. In oneembodiment, the initialization system 1081A monitors the position of thesecond stage 1040A when the second stage 1040A is rotated outside theworking ranges. In this embodiment, the initialization system 1081Aincludes one or more sensors which can measure position of the secondstage 1040A when the second stage 1040A is outside of the working rangesand/or over the full mechanical range of motion of the second stage1040A.

In the embodiment illustrated in FIG. 10A, the initialization system1081A includes six initial sensors 1083A-1083C (illustrated in phantom),namely (i) three spaced apart Z sensors 1083A that cooperate to measurethe position of the second stage 1040A relative to the first stage 1038Aalong the Z axis, about the X axis and about the Y axis, (ii) two spacedapart X sensors 1083B that cooperate to measure the position of thesecond stage 1040A relative to the first stage 1038A along the X axisand about the Z axis, and (iii) a Y sensor 1083C that measures theposition of the second stage 1040A relative to the first stage 1038Aalong the Y axis. Alternatively, for example, the initialization system1081A can include less than six or more than six sensors and/or one ormore of the sensors can reference movement relative to another structureother than the first stage 1038A.

In one embodiment, one or more of the initial sensors 1083A-1083C can bean absolute type sensor that has a fixed zero position. One such type ofsensor is a capacitance gauge. Other absolute type sensors includepotentiometers, LVDTS, and many optical sensors. With absolute typesensors 1083A-1083C, the desired orientation of the second stage 1040Aabout the X, Y and/or Z axes can be correlated to a particular set ofsensor values. The correct target values for the absolute type sensors1083A-1083C can be stored in the initialization software program of thecontrol system 24 (illustrated in FIG. 1). The use of absolute typesensors allows for relatively fast initialization of the interferometersystems 1023A-1023C.

In another embodiment, one or more of the initial sensors 1083A-1083Ccan be incremental type sensor that measures incremental movement of thesecond stage 1040A relative to the first stage 1038A. One suchincremental type sensor is an encoder.

In the embodiment illustrated in FIG. 10A, when the stage assembly 1020Ais first started, the initialization process begins, and the controlsystem controls the second mover assembly using the positionalinformation from the initial sensors 1083A-1083C. This control canoptionally happen at a relatively low initialization bandwidth. Withthis design, the second mover assembly is controlled to gradually movethe second stage 1040A from its initial position to the target position.Once the position of the second stage 1040A has stabilized in thecorrect orientation, the interferometer systems 1023A-1023C can beinitialized. Subsequently, the control system controls the second moverassembly using the positional information from the interferometersystems 1023A-1023C. Optionally the bandwidth can changed to a highervalue.

FIG. 10B is a simplified top perspective view of a portion of anotherembodiment of a stage assembly 1020B having features of the presentinvention. For example, the stage assembly 1020B can be used as thewafer stage assembly 20 or the reticle stage assembly 18 in the exposureapparatus 10 of FIG. 1. Alternatively, the stage assembly 1020B can beused to move other types of devices.

The components of the stage assembly 1020B that are illustrated in FIG.10B include a first stage 1038B, a second stage 1040B, a measurementsystem 1022B and an initialization system 1081B. The stages 1038B, 1040Band the measurement system 1022B can be similar in design to thecorresponding designs described above. In FIG. 10B, the measurementsystem 1022B again includes six interferometer systems 1023A-1023C thatcooperate to monitor the position of the second stage 1040A along threeaxes and about three axes.

In FIG. 10B, the initialization system 1081B again provides a way to getthe second stage 1040A aligned in the correct orientation when theinterferometer systems 1023A-1023C are not operational. In thisembodiment, the initialization system 1081A includes one or morealigners 1085A-1085C that inhibit further movement of the second stage1040A and that are positioned to cause the second stage 1040B to berotated within the respective working range.

In the embodiment illustrated in FIG. 10B, the initialization system1081B includes three aligners 1085A-1085C, namely a Z aligner 1085A, anX aligner 1085B, and a Y aligner 1085C. In this embodiment, the Zaligner 1085A includes three spaced apart Z hard stops 1087A(illustrated in phantom) that cooperate to inhibit movement of thesecond stage 1040B along the Z axis and that orientate the second stage1040B about the X and Y axes. The X aligner 1085B includes two spacedapart X hard stops 1087B that cooperate to inhibit movement of thesecond stage 1040B along the X axis and that orientate the second stage1040B about the Z axis. The Y aligner 1085C includes a Y hard stop 1087Cthat inhibits movement of the second stage 1040B along the Y axis.Alternatively, for example, the initialization system 1081B can includeless than three or more than three aligners. For example, the Y aligner1085C may not be necessary because, the other aligners 1085A, 1085B canbe used to properly orientate the second stage 1040B about the X, Y andZ axes.

In one embodiment, one or more of the hard stops 1087A-1087C includes acontact area 1089 that is made of a low-friction material or rollingelements (e.g., cam followers) to inhibit friction from hindering thealignment procedure.

Alternatively, for example, one or more of the hard stops can bereplaced with one or more limit switch or optical sensors.

In FIG. 10B, each of the stops 1087A-1087C is fixedly secured to thefirst stage 1038B and the contact area 1089 engages the second stage1040B. Alternatively, for example, one or more of the stops 1087A-1087Ccan be fixedly secured to another structure. For example, one or more ofthe stops 1087A-1087C can be secured to the second stage 1040B and thecontact area 1089 can engage the first stage 1038B or another structure.

In this embodiment, when the stage assembly 1020B is first started, theinitialization process begins, and the control system controls thesecond mover assembly in an open loop fashion without positionalinformation. With this design, the second mover assembly is controlledto gradually move the second stage 1040A from its initial position alongone axis (e.g. along the Z axis) until the second stage 1040A engagesthe respective stop(s) 1087A-1087C (e.g. the Z stops 1087A). Next, thesecond mover assembly is controlled to gradually move the second stage1040A along the next axis (e.g. along the X axis) until the second stage1040A engages the respective stop(s) 1087A-1087C (e.g. the X stops1087B). Finally, the second mover assembly is controlled to graduallymove the second stage 1040A along the remaining axis (e.g. along the Yaxis) until the second stage 1040A engages the respective stop(s)1087A-1087C (e.g. the Y stop 1087C).

Once the second stage 1040A is positioned against the stop(s)1087A-1087C, the interferometer systems 1023A-1023C can be initialized.Subsequently, the control system controls the second mover assemblyusing the positional information from the interferometer systems1023A-1023C. It should be noted that the X and Y interferometer systems1023B, 1023C can be initialized once the second stage 1040B engages theZ stops 1087A and the Z interferometer system 1023A can be initializedonce the second stage 1040B engages the X stops 1087B.

In certain designs, the activation of the movers in the second moverassembly occurs in a sequence that produces a repeatable alignment ofthe second stage 1040B.

FIG. 10C is a simplified top perspective view of a portion of yetanother embodiment of a stage assembly 1020C having features of thepresent invention. For example, the stage assembly 1020C can be used asthe wafer stage assembly 20 or the reticle stage assembly 18 in theexposure apparatus 10 of FIG. 1. Alternatively, the stage assembly 1020Ccan be used to move other types of devices.

The components of the stage assembly 1020C that are illustrated in FIG.10C include a first stage 1038C, a second stage 1040C, a measurementsystem 1022C and an initialization system 1081C. The stages 1038C, 1040Cand the measurement system 1022C can be similar in design to thecorresponding designs described above. In FIG. 10C, the measurementsystem 1022C again includes six interferometer systems 1023A-1023C thatcooperate to monitor the position of the second stage 1040C along threeaxes and about three axes.

In FIG. 10C, the initialization system 1081C includes a combination ofone or more initial sensors 1083A-1083C, and one or more aligners 1085A.

In the embodiment illustrated in FIG. 10C, the initialization system1081C includes (i) six initial sensors 1083A-1083C (illustrated inphantom), namely (i) three spaced apart Z sensors 1083A that cooperateto measure the position of the second stage 1040A along the Z axis,about the X axis and about the Y axis, (ii) two spaced apart X sensors1083B that cooperate to measure the position of the second stage 1040Aalong the X axis and about the Z axis, and (iii) a Y sensor 1083C thatmeasures the position of the second stage 1040A relative to the firststage 1038A along the Y axis, and (iv) a Z aligner 1085A (illustrated inphantom), including three spaced apart Z stops 1087A that cooperate toinhibit movement of the second stage 1040B along the Z axis and thatorientate the second stage 1040B about the X and Y axes.

In this embodiment, each of the Z sensors 1083A is an incremental typesensor and the X and Y sensors 1083B, 1083C are an absolute type sensor.In this embodiment, one or more of the Z measurers 406 (illustrated inFIGS. 4A and 9A) can be used as the Z sensors 1083A.

In this embodiment, when the stage assembly 1020B is first started, theinitialization process begins, and the control system controls thesecond mover assembly using positional information from the sensors1083A-1083C. With this design, the second mover assembly is controlledto gradually move the second stage 1040A from its initial position alongthe Z axis until the second stage 1040A engages the Z aligner 1085A.Further, the second mover assembly is controlled to gradually move thesecond stage 1040A from its initial position to the target positionalong the X and Y axes and about the Z axis using positional informationfrom the X and Y sensors 1083B, 1083C. Once the position of the secondstage 1040A has stabilized in the correct orientation, theinterferometer systems 1023A-1023C can be initialized. Subsequently, thecontrol system controls the second mover assembly using the positionalinformation from the interferometer systems 1023A-1023C.

As discussed above, the Z measurer 406 (illustrated in FIGS. 4A and 9A)for compensating the stiffness of the Z dampeners 410 can be an absolutetype sensor or an incremental type sensor. In the cases that one or moreof the Z measurers 406 are an absolute type sensor, the Z measurer 406can be used as the Z sensors 1083A of the initial sensors in theinitialization system 1081A and 1081C.

Semiconductor devices can be fabricated using the above describedsystems, by the process shown generally in FIG. 11A. In step 1101 thedevice's function and performance characteristics are designed. Next, instep 1102, a mask (reticle) having a pattern is designed according tothe previous designing step, and in a parallel step 1103 a wafer is madefrom a silicon material. The mask pattern designed in step 1102 isexposed onto the wafer from step 1103 in step 1104 by a photolithographysystem described hereinabove in accordance with the present invention.In step 1105, the semiconductor device is assembled (including thedicing process, bonding process and packaging process), finally, thedevice is then inspected in step 1106.

FIG. 11B illustrates a detailed flowchart example of the above-mentionedstep 1104 in the case of fabricating semiconductor devices. In FIG. 11B,in step 1111 (oxidation step), the wafer surface is oxidized. In step1112 (CVD step), an insulation film is formed on the wafer surface. Instep 1113 (electrode formation step), electrodes are formed on the waferby vapor deposition. In step 1114 (ion implantation step), ions areimplanted in the wafer. The above mentioned steps 1111-1114 form thepreprocessing steps for wafers during wafer processing, and selection ismade at each step according to processing requirements.

At each stage of wafer processing, when the above-mentionedpreprocessing steps have been completed, the following post-processingsteps are implemented. During post-processing, first, in step 1115(photoresist formation step), photoresist is applied to a wafer. Next,in step 1116 (exposure step), the above-mentioned exposure device isused to transfer the circuit pattern of a mask (reticle) to a wafer.Then in step 1117 (developing step), the exposed wafer is developed, andin step 1118 (etching step), parts other than residual photoresist(exposed material surface) are removed by etching. In step 1119(photoresist removal step), unnecessary photoresist remaining afteretching is removed. Multiple circuit patterns are formed by repetitionof these preprocessing and post-processing steps.

This invention can be utilized in an immersion type exposure apparatuswith taking suitable measures for a liquid. For example, PCT PatentApplication WO 99/49504 discloses an exposure apparatus in which aliquid is supplied to the space between a substrate (wafer) and aprojection lens system in exposure process. As far as is permitted, thedisclosures in WO 99/49504 are incorporated herein by reference.

Further, this invention can be utilized in an exposure apparatus thatcomprises two or more substrate and/or reticle stages. In suchapparatus, the additional stage may be used in parallel or preparatorysteps while the other stage is being used for exposing. Such a multiplestage exposure apparatus are described, for example, in Japan PatentApplication Disclosure No. 10-163099 as well as Japan Patent ApplicationDisclosure No. 10-214783 and its counterparts U.S. Pat. No. 6,341,007,U.S. Pat. No. 6,400,441, U.S. Pat. No. 6,549,269, and U.S. Pat. No.6,590,634. Also it is described in Japan Patent Application DisclosureNo. 2000-505958 and its counterparts U.S. Pat. No. 5,969,411 as well asU.S. Pat. No. 6,208,407. As far as is permitted, the disclosures in theabove-mentioned U.S. Patents, as well as the Japan Patent Applications,are incorporated herein by reference.

This invention can be utilized in an exposure apparatus that has amovable stage retaining a substrate (wafer) for exposing it, and a stagehaving various sensors or measurement tools for measuring, as describedin Japan Patent Application Disclosure 11-135400. As far as ispermitted, the disclosures in the above-mentioned Japan patentapplication are incorporated herein by reference.

While the current invention is disclosed in detail herein, it is to beunderstood that it is merely illustrative of the presently preferredembodiments of the invention and that no limitations are intended to thedetails of construction or design herein shown other than as describedin the appended claims.

1. A stage assembly that positions a work piece about a first axis, thestage assembly comprising: a first stage; a second stage that retainsthe work piece; a second mover assembly that moves the second stagerelative to the first stage about the first axis; a measurement systemthat monitors the position of the second stage about the first axis whenthe second stage is positioned within a FA working range about the firstaxis; and an initialization system that facilitates positioning of thesecond stage about the first axis when the second stage is rotated aboutthe first axis outside the FA working range.
 2. The stage assembly ofclaim 1 wherein the initialization system monitors the position of thesecond stage about the first axis.
 3. The stage assembly of claim 1wherein the measurement system monitors the position of the second stageabout a second axis when the second stage is positioned within a SAworking range and wherein the initialization system monitors theposition of the second stage about the first axis and the second axis.4. The stage assembly of claim 3 wherein the measurement system monitorsthe position of the second stage about a third axis when the secondstage is positioned within a TA working range and wherein theinitialization system monitors the position of the second stage aboutthe third axis.
 5. The stage assembly of claim 1 wherein theinitialization system includes a first aligner and wherein the secondmover assembly moves the second stage against the first aligner toorientate the second stage within the FA working range.
 6. The stageassembly of claim 5 wherein the initialization system includes a secondaligner and wherein the second mover assembly moves the second stageagainst the second aligner to orientate the second stage within a SAworking range.
 7. The stage assembly of claim 6 wherein theinitialization system includes a third aligner and wherein the secondmover assembly moves the second stage against the third aligner toorientate the second stage within a TA working range about the thirdaxis.
 8. The stage assembly of claim 5 wherein the first alignerincludes a contact area that allows the second stage to move relative tothe first aligner while engaging the first aligner.
 9. The stageassembly of claim 1 wherein the initialization system includes a firstsensor that monitors the position of the second stage and a firstaligner, and wherein the second mover assembly moves the second stageagainst the first aligner to orientate the second stage within the FAworking range.
 10. The stage assembly of claim 1 further comprising afirst mover assembly that moves the first stage with three degrees ofmovement.
 11. The stage assembly of claim 1 wherein the second moverassembly includes a mover and a dampener that reduces the transmissionof vibration from the first stage to the second stage, and the stageassembly further comprises a control system that directs power to themover to compensate for vibration from the first stage.
 12. An exposureapparatus including an illumination system and the stage assembly ofclaim
 1. 13. A method for manufacturing a device, the method comprisingthe steps of providing a substrate and forming an image on the substratewith the exposure apparatus of claim
 12. 14. A method for manufacturinga wafer, the method comprising the steps of providing a substrate andforming an image on the wafer with the exposure apparatus of claim 12.15. The stage assembly of claim 1 wherein the second mover assemblyincludes a dampener that reduces the transmission of vibration from thefirst stage to the second stage, and a detector that detects thepositional information related to the motion of the dampener along thefirst axis, and the stage assembly further comprises a control systemthat compensates for vibration from the first stage utilizing theinformation detected by the detector, the initialization systemmonitoring the position of the second stage by utilizing the detector.16. A method for positioning a work piece about a first axis, the methodcomprising the steps of: providing a first stage; providing a secondstage that retains the work piece; moving the second stage relative tothe first stage about the first axis with a second mover assembly;monitoring the position of the second stage about the first axis whenthe second stage is positioned within a FA working range about the firstaxis with a measurement system; and initializing the measurement systemwith an initialization system that facilitates positioning of the secondstage about the first axis when the second stage is rotated about thefirst axis outside the FA working range.
 17. The method of claim 16wherein the initialization system monitors the position of the secondstage about the first axis.
 18. The method of claim 16 wherein the stepof monitoring the position includes the step of monitoring the positionof the second stage about a second axis when the second stage ispositioned within a SA working range and wherein the step ofinitializing includes monitoring the position of the second stage aboutthe first axis and the second axis.
 19. The method of claim 16 whereinthe initialization system includes a first aligner and wherein the stepof moving includes moving the second stage against the first aligner toorientate the second stage within the FA working range.
 20. The methodof claim 19 wherein the initialization system includes a second alignerand wherein the step of moving includes moving the second stage againstthe second aligner to orientate the second stage within a SA workingrange.
 21. The method of claim 19 wherein the first aligner includes acontact area that allows the second stage to move relative to the firstaligner while engaging the first aligner.
 22. The method of claim 16wherein the initialization system includes a first sensor that monitorsthe position of the second stage and a first aligner, and wherein thestep of moving includes moving the second stage against the firstaligner to orientate the second stage within the FA working range. 23.The method of claim 16 further comprising the step of moving the firststage with three degrees of movement with a first mover assembly.
 24. Amethod for exposing on a work piece, the method comprising the steps ofgenerating a beam and positioning the work piece in the path of the beamby the method of claim
 16. 25. A stage assembly that positions a workpiece about a first axis, the stage assembly comprising: a first stage;a second stage that retains the work piece; a second mover assembly thatmoves the second stage relative to the first stage about the first axis;a measurement system that monitors the position of the second stageabout the first axis when the second stage is positioned within a FAworking range about a second axis that is orthogonal to the first axis;and an initialization system that facilitates positioning of the secondstage about the first axis when the second stage is rotated about thesecond axis outside the FA working range.